Hi Marc,
Check out this excellent website link that was provided by a member of this bulletin board:
http://alfacentro.com/features/gtjr/p0015.html
The removal of my outer rusted out rocker panels was not difficult once I had viewed the numerous web links in the restoration section of the BB about the process. Although I know how to TIG weld body panels, I had never worked on a unibody car before so I'm learning too. This is my first Alfa project so I'm trying to learn from others who have already done it prior to attempting any work on my car. As you can see from my other postings, I usually ask about something before I actually do it.
I used a cut-off disk in my grinder to make a small slice between the spot welds on the outer panel (just like the above web link describes) and used a small cold chisel to pry the outer panel off. Mine were so rusted, that a slight tap of the hammer on the chisel easily broke the piece free. I had the entire outer rocker panel off in about an hour. Then I put a medium wire brush in my grinder and removed the rust scale on the middle panel. Then I used a fine brush in the grinder to remove the surface rust to prep the area for TIG welding. I'm planning to use the POR-15 system to coat all of the exposed areas prior to TIG welding in the new outer panels.